Microlattice ballistic helmet pads

ABSTRACT

A helmet pad includes a substrate having first side attachable to an interior surface of a helmet. The helmet pad includes an outer lattice layer peripherally attached to a second side of the substrate. The second side is opposite to the first side. In one embodiment, the outer lattice layer includes fibers attached in one of: (i) a Voronoi lattice unit cells; and (ii) tetrahedral lattice unit cells. The helmet pad includes padding material received in an enclosure between the second surface of the substrate and the outer lattice layer.

FIELD OF THE INVENTION

The present disclosure generally relates to microlattice helmet pads attached to an interior of a helmet, and more particularly to helmets pads that absorb ballistic impact to the helmet.

BACKGROUND OF THE INVENTION

During a collision, helmets protect users in at least two different ways: (a) preventing penetration of the scalp and skull; and (b) distributing the force of blunt impacts to make other injury types less severe. To accomplish the second objective, most helmets are lined with impact-absorbing pads. And for some time, foam has been the material of choice. Foam has made helmet padding inexpensive and relatively effective. Moreover, the offerings have evolved greatly over the years. Ingenious combinations of materials, such as by the applicant, effectively and comfortably resist impacts. But challenges remain. Many pads are designed too stiffly - a problem that can make impacts to the brain far worse. Concussions remain difficult to prevent and to detect. And on the battlefield, shockwaves from improvised explosive devices can still cause lasting injuries even through state-of-the-art headgear.

SUMMARY OF THE INVENTION

In one aspect, the present disclosure provides a helmet pad comprising a substrate having first side attachable to an interior surface of a helmet shell. The helmet pad comprises an outer lattice layer peripherally attached to a second side of the substrate. The second side is opposite to the first side. The outer lattice layer comprises a lattice structure attached in one of: (i) a Voronoi lattice unit cells; and (ii) tetrahedral lattice unit cells. Padding material is received in an enclosure between the second surface of the substrate and the outer lattice layer.

In another aspect, the present disclosure provides a helmet having one or more helmet pads attached to an interior surface of a helmet shell. Each helmet pad comprises an outer lattice layer peripherally attached to a second side of the substrate. The second side is opposite to the first side. The outer lattice layer comprises elastomer attached in one of: (i) a Voronoi lattice unit cells; and (ii) tetrahedral lattice unit cells. Padding material is received in an enclosure between the second surface of the substrate and the outer lattice layer.

The present disclosure is directed to various embodiments of a 3D microlattice layer and/or structure having a plurality of interconnected filaments and/or and one or more material layers. The various improved microlattice structures provided herein may be fabricated using polymers such as an elastomeric polymer.

The microlattice structures may comprise an elastomer. In some embodiments, the microlattice structures may comprise silicone, polyurethane, polyacrylate, and/or any similar polymer, or combinations of polymers. The microlattice structures may be made from a material having an elastic modulus of 10 kPa to 100 MPa, inclusive, or any value or range therebetween. The microlattice structures may be, for example, a lattice, such as a polymer lattice (see, for example, FIGS. 1A, 1C, and 1D). In non-limiting embodiments having polymer lattice substrates, the polymer lattice is made up of a plurality of struts. The struts may have strut diameters of 0.5 mm to 2.5 mm, including all 0.001 mm values and ranges therebetween. In other embodiments, struts may have larger or smaller diameters. Within a lattice, struts need not have the same diameters. For example, as further described in the Exemplary Embodiments below, the lattice may have regions with differing rigidity where the struts have different diameters. Other strut characteristics (e.g., material(s), length, shape, etc.) may also be designed to provide lattice properties advantageous in a given application.

Any elastomer that provides the desired properties (e.g., is flexible and can be formed to the desired shape by 3D printing, molding or another method) can be employed. For example, elastomers having one or more of a Shore A hardness within the ranges described herein, tensile strength within the ranges described herein and elongation at break within the ranges described herein, can potentially be employed. As examples, the elastomeric material can be polyurethane, polyethylene plastic, rubber or mixtures thereof. In an example, the elastomeric polymer is photocurable. Commercial examples of suitable elastomeric polymers include TPU 92A, available from Stratasys LTD, of Rehovot, Israel; and UV-cured urethane elastomer EPU40 and EPU41 (Carbon Inc., Redwood City, CA, USA). The 3D microlattice layer provides many advantages because they can endure sequential impacts without complete failure and also absorb energy equal to or improved to conventional impact absorbing materials. The microlattice structures of the present disclosure may be incorporated into any desired protective garment necessary for impact protection, vibration protection, comfort and/or acoustic damping.

The elastomeric material is chosen to provide properties that can aid in achieving both the desired durability and compressibility of the compressible part, including a desired hardness, tensile strength and elongation at break. As examples, the elastomeric material may have a Shore A Hardness of from about 40 to about 100, such as about 50 to about 90, such as about 60 to about 80, or about 65 to about 75, or about 68 to about 73, or from about 70 to about 72, or about 70. In another example, the elastomeric material has a tensile strength of, for example, from about 5 MPa to about 15 MPa, such as about 8 MPa to about 12 MPa, or about 10 MPa to about 11 MPa. In another example, the elastomeric material has an elongation at break of, for example, about 210% to about 410%, such as about 230% to about 390%, or about 240% to about 480%. Employing materials with hardness, tensile strength and elongation at break within these ranges can provide for compressible parts that last for long periods of time without fatiguing out. The tensile strength and elongation at break can be determined using ASTM D412.

The various improved microlattice structures provided herein are depicted with respect to a tactical ballistic helmet, but it should be understood that the various devices, methods and/or components may be suitable for use in protection in various other athletic sports, and other occupations that require personal protective equipment, such as auto, aerospace, law enforcement, military, construction and/or informal training session uses. For example, the embodiments of the present invention may be suitable for use by individuals engaged in athletic activities such as baseball, bowling, boxing, cricket, cycling, motorcycling, golf, hockey, lacrosse, soccer, rowing, rugby, running, skating, skateboarding, skiing, snowboarding, surfing, swimming, table tennis, tennis, or volleyball, or during training sessions related thereto.

The particular configuration of the microlattice structures can be chosen to provide the desired compressibility and durability. For example, increasing the percentage of polymer material per unit volume of the lattice, thereby decreasing the volume of air gaps in the lattice, will decrease the compressibility; while decreasing the percentage of polymer material per unit volume will increase the compressibility. The percentage of polymer material per unit volume can be as low as 5% or as high as 95% depending on the stiffness desired. The lattice can have lattice patterns that include any geometrical shape. For example, a lattice pattern comprised of rectangular, diamond, triangle or other polygon patterns having from about 3 to about 10 sides, or about 4 to about 8 sides, circular or oval shape patterns, spiral patterns or any other suitable lattice pattern. Diamonds shapes are easiest to design. With 3D printing technology, the ability to create a variety of other shapes, such as spiral, spring like structures, is possible, as the structure can be strong enough to self-support during fabrication. The lattice can have a single pattern or multiple different patterns as part of the same lattice structure.

In one embodiment, the 3D microlattice layers may comprise one or more material layer(s) to improve the mechanical properties of the microlattice layer or structure. The one or more material layers may be configured to increase the compressive strength and stiffness of the microlattice structure. In one or more embodiments, the material layer transversely and rotationally constrains a plurality of nodes of the microlattice structure and thereby increases the overall compressive strength and stiffness of the microlattice structure. The one or more material layers may be fixed or removably coupled to the 3D microlattice layer.

In another embodiment, the microlattice layer and/or structures can receive multiple impacts and recover to its original shape after impact. During the impact load, at least a portion of the microlattice layer and/or structure may experience a large deflection with global and/or local elastic buckling of the plurality of filaments and/or the one or more nodes where the plurality of filaments intersect. In another embodiment, once the impact load is removed, the microlattice layer recovers to its original shape and height after experiencing compressive strains in excess of 50% without plastic deformation. The buckling being a sudden lateral deflection away from the plurality interconnected filaments' longitudinal axis. In another embodiment, the buckling of the microlattice layer may comprise buckling in a single direction or in multiple directions. The buckling may be asymmetrical or symmetrical throughout the microlattice layer.

In another embodiment, the microlattice layer and/or structure can be optimized for uniform energy absorption. The filament dimensions, filament material, the filament units, interior angles, the connecting members, and the material layers can be tuned to design the appropriate buckling strength and buckling location, compression strength and shear strength depending on the application and loading conditions. For example, the compression and shear properties (modulus and strength) are highly dependent on the filament interior angles. Therefore, for the same material and density, the filament interior angle can be changed to either increase or decrease the buckling strength.

In another embodiment, the microlattice layer and/or structure can be optimized for specific impact absorption that requires non-uniform impact absorption in different regions. Different sports and occupations include differences in the type, severity and/or frequency of impacts that a wearer could experience. The microlattice layer and/or structure may comprise one or more segments and/or one or more regions that have specific impact absorption properties.

The non-uniform mechanical characteristics comprises two or more regions having different impact absorption properties. The impact absorption properties may be modified in each region by changing the filament dimensions, filament material, filament units, interior angles, compressive strength, compressive strain, and/or density of the microlattice. Alternatively, the microlattice layer may comprise a plurality of microlattice segments, the plurality of microlattice segments having different impact absorption and/or mechanical properties to the adj acent plurality of microlattice structures. Alternatively, at least one of the microlattice segments from the plurality of microlattice segments have different impact absorption and/or mechanical properties. The microlattice layer may comprise a uniform density or a non-uniform density. The microlattice layer may comprise a uniform compressive strain or a non-uniform compressive strain. The microlattice layer may comprise the same filament geometric units throughout the microlattice layer and/or different filament geometric units throughout the microlattice layer.

In another embodiment, the microlattice layer and/or structure comprises a plurality of filaments, the plurality of filaments having or sharing at least one interconnection or node to an adjacent plurality of filaments. The plurality of filaments having a longitudinal axis and/or the adjacent plurality of filaments having a longitudinal axis, the plurality of filaments longitudinal axis and the adjacent plurality of filaments longitudinal axis extending in different directions. The different directions may comprise lateral direction, perpendicular direction, non-perpendicular direction. The non-perpendicularity may comprise having an interior angle of 1 degree to 89 degrees. Alternatively, the non-perpendicularity may comprise an interior angle of 15 degrees to 75 degrees. The plurality of filaments and/or the adjacent plurality of filaments having a 3:1 or greater aspect ratio and having a cross-section, the cross-section is solid or hollow. The cross-section may further comprise a circle, a regular polygon or irregular polygon. The plurality of filaments and/or the adjacent plurality of filaments are spaced apart, and positioned parallel in a straight line, with repeating rows or non-repeating rows. Alternatively, the plurality of filaments and/or the adjacent plurality of filaments are positioned offset or staggered, repeating rows and/or non-repeating rows that are staggered, offset, and/or diagonal alignment from the adjacent or preceding row--the staggered, offset and/or diagonal alignment may be a 15 to 60 degree alignment. The microlattice layer and/or structure may further comprise at least one material layer. Alternatively, the microlattice layer and/or structure may further comprise a first material layer and a second material layer. The microlattice layer and/or structure may be a single structure and/or layer, and/or a plurality of layers or structures. The plurality of layers and/or structures may be stacked longitudinally, or positioned adjacent to preceding plurality of layers or structures.

In another embodiment, the microlattice layer and/or structure comprises a first plurality of filaments and a second plurality of filaments, the first plurality of filaments having or sharing at least one interconnection (or node) with the second plurality of filaments. The first plurality of filaments having a longitudinal axis and/or the second plurality of filaments having a longitudinal axis, the first plurality of filaments longitudinal axis and the second plurality of filaments longitudinal axis extending in different directions. The non-perpendicularity may comprise having an interior angle of 1 degree to 89 degrees. Alternatively, the non-perpendicularity may comprise an interior angle of 15 degrees to 75 degrees. The first plurality of filaments and/or the second plurality of filaments having a 3:1 or greater aspect ratio and having a cross-section, the cross-section is solid and/or hollow. The cross-section may further comprise a circle, a regular polygon or irregular polygon. The first plurality of filaments and/or the second plurality of filaments are spaced apart, and positioned parallel in a straight line, with repeating rows, non-repeating rows and/or random rows. Alternatively, the first plurality of filaments and/or the second plurality filaments are positioned offset or staggered, repeating rows, non-repeating rows and/or random rows that are staggered, offset, and/or diagonal alignment from the adjacent or preceding repeating row or non-repeating row--the staggered, offset and/or diagonal alignment may be a 15 to 60 degree alignment. The microlattice layer and/or structure may further comprise at least one material layer. Alternatively, the microlattice layer and/or structure may further comprise a first material layer and a second material layer. The microlattice layer and/or structure may be a single structure and/or layer, and/or a plurality of layers or structures. The plurality of layers and/or structures may be stacked longitudinally, or positioned adjacent to preceding plurality of layers or structures.

In another embodiment, the microlattice layer and/or structure comprises at least three filaments, at least one node and a plurality of interior angles. The at least three filaments having a longitudinal axis, the at least three filaments longitudinal axis extending in different directions from the at least one node. The at least three filaments connecting, coupling and/or fusing to the adjacent at least three filaments to create a matrix or microlattice. The plurality of interior angles disposed between each of the at least three filaments. The plurality of interior angles comprises perpendicular and/or non-perpendicular angles. The non-perpendicularity may comprise having an interior angle of 1 degree to 89 degrees. Alternatively, the non-perpendicularity may comprise an interior angle of 15 degrees to 75 degrees. The at least three filaments having a 3:1 or greater aspect ratio and having a cross-section, the cross-section is solid and/or hollow. The cross-section may further comprise a circle, a regular polygon or irregular polygon. The at least three filaments are spaced apart, and positioned parallel in a straight line, with repeating rows, non-repeating rows and/or random rows. Alternatively, the at least three filaments are positioned offset or staggered, repeating rows, non-repeating rows and/or random rows that are staggered, offset, and/or diagonal alignment from the adjacent or preceding row--the staggered, offset and/or diagonal alignment may be a 15 to 60 degree alignment. The microlattice layer and/or structure may further comprise at least one material layer. Alternatively, the microlattice layer and/or structure may further comprise a first material layer and a second material layer. The microlattice layer and/or structure may be a single structure and/or layer, and/or a plurality of layers or structures. The plurality of layers and/or structures may be stacked longitudinally, or positioned adjacent to preceding plurality of layers or structures.

In another embodiment, the microlattice layer and/or structure comprising a plurality of filament units. The plurality of filament units comprises a plurality of interconnected filaments arranged into an array of geometric shapes. The plurality of interconnected filaments having at least one node disposed at the intersections between the plurality of interconnected filaments. The geometric shapes may comprise regular or irregular polygons. The geometric shapes may comprise 2D or 3D shapes. The geometric shapes may further comprise a 2D or 3D triangular, cubic, star, octet, hexagonal, diamond, tetrahedron, kegome and/or any combination thereof. The plurality of filaments having a cross-sectional shape, the cross-sectional shape may be solid or hollow. The cross-sectional shape may be circular, oval, regular polygon and/or irregular polygon. the plurality of interconnected filaments extending from the at least one node. The microlattice layer and/or impact mitigation layer further comprising interior angles, the interior angles disposed between the plurality of interconnected filaments. In another example, the interior angle(s) comprising 1 degree to 89 degrees. Alternatively, the interior angle(s) angles comprising 15 degrees to 75 degrees. In another example, the plurality of interconnected filaments having a 3:1 or greater aspect ratio and having a cross-section, the cross-section is solid and/or hollow. The cross-section may further comprise a circle, a regular polygon or irregular polygon. The plurality of geometric filament units are spaced apart, and positioned parallel in a straight line, with repeating rows, non-repeating rows and/or random rows.

In another embodiment, the microlattice layer and/or structure comprises a plurality of nodes, a plurality of filaments and a plurality of interior angles. The plurality of filaments extends from each of the plurality of nodes. The plurality of interior angles disposed between the plurality of filaments. The plurality of interior angles comprises perpendicular or non-perpendicular angles. The plurality of interior angles comprises a range of 1 to 89 degrees. Alternatively, the interior angle(s) angles comprising 15 degrees to 75 degrees. The plurality of filaments having a 3:1 or greater aspect ratio and having a cross-section, the cross-section comprising a solid and/or hollow cross-section. The solid or hollow cross-section may further comprise a circle, a regular polygon or irregular polygon. The plurality of filaments and/or each of the plurality of filaments extending in the same direction and/or different directions from each of the plurality of nodes. Alternatively, the plurality of filaments and/or each of the plurality of filaments extending in the same plane and/or different planes.

In another embodiment, the microlattice layer and/or structure comprises a plurality of filaments, an additional plurality of filaments and a plurality of interior angles. The plurality of filaments or each of the plurality of filaments comprising a first end node and/or a second end node. The plurality of filaments or each of the plurality of filaments further comprising at least one mid node, the at least one mid node disposed anywhere along the length of the plurality of filaments or each of the plurality of filaments between the first and second end node. The additional plurality of filaments and/or each of the additional plurality of filaments extends from the first or second end node of the plurality of filaments or each of the first or second end node of the plurality of filaments. Accordingly, the additional plurality of filaments and/or each of the additional plurality of filaments extends from the first end and second end of the plurality of filaments or each of the first end and second end of the plurality of filaments. Furthermore, the additional plurality of filaments and/or each of the additional plurality of filaments extends from the first end node, second end node, and the at least one mid node of the plurality of filaments or each of the first end of the plurality of filaments. Alternatively, the additional plurality of filaments and/or each of the additional plurality of filaments extends from the first end node or second end node, and the at least one mid node of the plurality of filaments or each of the first end of the plurality of filaments. The plurality of interior angles disposed between the plurality of filaments and the additional plurality of filaments. In one example, the plurality of interior angles comprises perpendicular or non-perpendicular angles. In another example, the plurality of interior angles comprises a range of 1 to 89 degrees. Alternatively, the interior angle(s) angles comprising 15 degrees to 75 degrees. The plurality of filaments having a 3:1 or greater aspect ratio and having a cross-section, the cross-section comprising a solid and/or hollow cross-section. The solid or hollow cross-section may further comprise a circle, a regular polygon or irregular polygon. The plurality of filaments and/or each of the plurality of filaments extending in the same direction and/or different directions from each of the plurality of nodes. Alternatively, the additional plurality of filaments and/or each of the additional plurality of filaments extending in the same plane and/or different planes as the plurality of filaments or each of the plurality of filaments.

In another embodiment, the microlattice layer and/or structure comprises a plurality of filaments, a plurality of nodes and a plurality of interior angles. The plurality of filaments intersects creating the plurality of nodes at the intersection. The plurality of nodes comprising a first end node and/or a second end node. The first and second end node disposed on the top or bottom portion of the plurality of filaments. In one example, the plurality of nodes further comprising at least one mid node, the at least one mid node disposed anywhere along the length of the plurality of filaments or each of the plurality of filaments between the first and second end node. In another example, the plurality of nodes comprising 1 to 10 nodes. The plurality of filaments and/or each of the plurality of filaments extends from the plurality of nodes. In another embodiment, the plurality of filaments extends from the first end or second end node. In another embodiment, the plurality of filaments and/or each of the plurality of filaments extends non-perpendicular from the first end node, second end node, and the at least one mid node. Alternatively, the plurality of filaments and/or each of the plurality of filaments extends from the first end node or second end node, and the at least one mid node. The plurality of interior angles disposed between the plurality of filaments. The plurality of interior angles comprises perpendicular or non-perpendicular angles. The plurality of interior angles comprises a range of 1 to 89 degrees. Alternatively, the interior angle(s) angles comprising 15 degrees to 75 degrees. The plurality of filaments having a 3:1 or greater aspect ratio and having a cross-section, the cross-section comprising a solid and/or hollow cross-section. The solid or hollow cross-section may further comprise a circle, a regular polygon or irregular polygon. The plurality of filaments and/or each of the plurality of filaments extending in the same direction and/or different directions from each of the plurality of nodes.

In another embodiment, the microlattice layer may comprise a plurality microlattice layers and/or structures that are stacked. The stacking may comprise a plurality of microlattice layers disposed or arranged on top of each other longitudinally. The plurality of microlattice layers and/or each of the plurality of microlattice layers having the same microlattice density, microlattice compressive strain, microlattice compressive strength, filament dimensions, filament units, interior angles, and/or the any combination thereof. Alternatively, the plurality of microlattice layers and/or each of the plurality of microlattice layers having the different microlattice densities, microlattice compressive strain, microlattice compressive strength, filament dimensions, filament units, interior angles, and/or the any combination thereof. The plurality of microlattice layers and/or each of the plurality of microlattice layers may be aligned or non-aligned (e.g., offset) with one or more nodes, and/or one or more filaments.

In one or more embodiments, the filaments that comprise the material within the microlattice layer and the material may be varied. The filaments may comprise a material, the material including thermoplastic elastomers, thermoset elastomers, thermosets, and/or thermoplastics. The filaments may comprise a material, the material being a foam. The foam can include polymeric foams, quantum foam, polyethylene foam, polyurethane foam (PU foam rubber), XPS foam, polystyrene, phenolic, memory foam (traditional, open cell, or gel), impact absorbing foam, compression foam, latex rubber foam, convoluted foam (“egg create foam”), EVA foam, VN 600 foam, Evlon foam, Ariaprene or Ariaprene-like material, PORON XRD, impact hardening foam, and/or any combination thereof. The at least one foam layer may have an open-cell structure or closed-cell structure. The foam layer can be further tailored to obtain specific characteristics, such as anti-static, breathable, conductive, hydrophilic, high-tensile, high-tear, controlled elongation, and/or any combination thereof. The material may be uniform throughout the microlattice layer, and/or non-uniform throughout the microlattice layer.

In one or more embodiments, the microlattice layer may comprise at least one material layer including at least one surface that conforms to an anatomical feature of a wearer. The at least one material layer including at least one surface can generally match, match or substantially match the wearer’s unique anatomical features, namely the topography and contours of the wearer’s head and facial region, including the jaw region. Accordingly, the at least one material layer may comprise a first surface (or top surface) and a second surface (or a bottom surface), the first surface or second surface can generally match, match or substantially match the wearer’s anatomical features and/or the contours of a wearer’s head. Such custom surfaces provide an improved fit and comfort for the wearer, and interchangeability.

Due to the main characteristic of the device being its flexible structure, FIGS. 1-8 can be manufactured from elastomer, various polymer materials, elastomeric polymers, plastics, thermoplastics, polyurethanes, resins and interwoven fibers infused with resin, molded rubbers or other rubber-like materials, and filament materials, among others. The device would be available in various sizes and durometers and the manufacturing processes may include various elastomeric printing processes and techniques, carbon digital light synthesis printing (DLS), continuous liquid interface production (CLIP), stereolithography printing, injection molding and urethane casting among other processes.

These and other features are explained more fully in the embodiments illustrated below. It should be understood that in general the features of one embodiment also may be used in combination with features of another embodiment and that the embodiments are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The various exemplary embodiments of the present invention, which will become more apparent as the description proceeds, are described in the following detailed description in conjunction with the accompanying drawings, in which:

FIG. 1A depicts a three-dimensional view of a set of three example MLB helmet pads, according to one or more embodiments;

FIG. 1B depicts a top outline view of the set of three MLB helmet pads of FIG. 1A, according to one or more embodiments;

FIG. 2 depicts a three-dimensional view of an example MLB helmet pad formed from tetrahedral lattice unit cells, according to one or more embodiments;

FIG. 3 depicts a three-dimensional view of an example MLB helmet pad formed from Voronoi lattice unit cells, according to one or more embodiments;

FIG. 4 depicts a three dimensional view of three versions of MLB helmet pad of FIG. 3 , according to one or more embodiments;

FIG. 5 depicts a side view of the MLB helmet pad of FIG. 4 , according to one or more embodiments;

FIG. 6 depicts a top view of a set of example MLB helmet pads having selectable Voronoi and tetrahedral lattice unit cells, according to one or more embodiments;

FIG. 7 depicts a three-dimensional detail view of one MLB helmet pad of FIG. 6 , according to one or more embodiments;

FIG. 8 depicts a bottom view of the set of MLB helmet pads of FIG. 6 attached to an interior of a tactical helmet, according to one or more embodiments;

FIG. 9 depicts a graphical chart comparing back face deformation test results of a conventional helmet pad and the example MLB helmet pad, according to one or more embodiments;

FIG. 10 depicts a graphical chart comparing blunt impact test results of a conventional helmet pad and the example MLB helmet pad, according to one or more embodiments;

FIG. 11 depicts a top view of a hybrid set of example MLB helmet pads with a recessed top foam layer, according to one or more embodiments;

FIG. 12 depicts a top view of a set of MLB helmet pads that provide substantially full cranial coverage, according to one or more embodiments;

FIG. 13 depicts a three-dimensional view of an example set of the MLB helmet pads of FIG. 12 having a first thickness, according to one or more embodiments;

FIG. 14 depicts a three-dimensional view of another example set of the MLB helmet pads of FIG. 12 having a second thickness, according to one or more embodiments;

FIG. 15 depicts a three-dimensional view of the example set of the MLB helmet pads of FIG. 12 conformed to a cranium of a user, according to one or more embodiments;

FIG. 16 depicts a side cutaway view of the example set of the MLB helmet pads of FIG. 12 conformed to a cranium of a user, according to one or more embodiments; and

FIG. 17 depicts a three-dimensional view of the example set of the MLB helmet pads of FIG. 12 attached inside a helmet, according to one or more embodiments.

DETAILED DESCRIPTION

FIG. 1A depicts a three-dimensional view of an example set 100 of three example micro-lattice ballistic (MLB) helmet pads 101 - 103, in particular a front MLB helmet pad 101, a lateral MLB helmet pad 102, and a back MLB helmet pad 103. FIG. 1B depicts a top outline view of the set 100 of three MLB helmet pads 101 - 103. The set 100 shares a similar shape to a convention set of polymer-encased foam helmet pads, enabling retrofitting with a similar form-fit-function. Each MLB helmet pads 101 - 103 having three raised lateral pad portions 105 on a substrate 107. Gaps 109 between pad portions 105 and radial recesses 110 formed in particular pad portions 105 facilitate conformal bending of the MLB helmet pads 101 - 103 to conform to an internal surface of a helmet. With particular reference to FIG. 1A, each lateral pad portions 105 of each MLB helmet pad 101 - 103 enables air flow by having an outer lattice layer 109 peripherally attached to the substrate 107. The outer lattice layer 113 comprises elastomers attached in one of: (i) a Voronoi lattice unit cells; and (ii) tetrahedral lattice unit cells. Padding material is received in an enclosure between the substrate 107 and the outer lattice layer 113. In one or more embodiments, the padding material comprises one or more internal lattice layers peripherally attached to the second side of the substrate. The one or more internal lattice layers each comprise elastomers attached in one of: (i) a Voronoi lattice unit cells; and (ii) tetrahedral lattice unit cells.

In one or more embodiments, the fibers are additively manufactured using EPU 41 elastomeric material from Carbon®, Carbon, Inc., based in Redwoods, CA. In one or more embodiments, the lattice layers are sufficiently small in size to be referred to as “microlattices”. In one or more embodiments, the microlattices are formed using an approach by Carbon® referred to as Carbon Digital Light Synthesis™ (Carbon DLS™), which combines a range of technologies—including digital light projection and specialized resins-to make microscale manufacturing more precise, consistent, and cost-effective. At the heart of Carbon DLS is a process called continuous liquid interface production (CLIP). CLIP reduces the expense of 3D printing significantly, making it possible for more companies to create their own microlattice-based materials. 3D-printed materials typically begin as resins that are hardened using ultraviolet (UV) light. With CLIP, an image made of UV light is projected through a window onto the resin. That causes cross-section of the part to (partially) cure. The printed section moves out of the way and the process is repeated, producing a material with consistent strength and design. The component is then baked in a thermal bath or oven to toughen and cure. Before light hits the resin, each projected image first passes through a “dead zone” that is thinner than a human hair and that is a resin-oxygen mixture that prevents UV curing. In essence, the resin-oxygen mixture serves as a membrane that keeps the printed part from sticking to the machine. The dead zone creates just the barrier needed to skip slow, potentially damaging peeling processes.

FIG. 2 depicts a three-dimensional view of an example MLB helmet pad 200 formed from tetrahedral lattice unit cells 201 that provide a foam-like nonlinear stress-strain response. FIG. 3 depicts a three-dimensional view of an example MLB helmet pad 300 formed from Voronoi lattice unit cells 301 that provide a constant force stress plateau. To vary designed stiffness within a part having constant strut diameter, increasing cell size results in a stiffer pad. Decreasing strut diameter thus results in a softer pad. To vary designed stiffness within a part with constant cell size, increasing diameter of the struts or filaments results in a stiffer pad. Decreasing cell size thus results in a stiffer pad.

FIG. 4 depicts a three dimensional view of two versions of a MLB helmet pad of FIG. 3 . MLB helmet pad 400 a is a half-inch thick with an outer lattice layer 401 a formed from tetrahedral lattice unit cells 403 attached to a rounded rectangular substrate 407. MLB helmet pad 400 b is an inch thick with an outer lattice layer 401 b also formed from tetrahedral lattice unit cells 403 attached to the rounded rectangular substrate 407. Padding material 415 of MLB helmet pad 400 b is formed of stacked internal layers 417 of tetrahedral lattice unit cells 403.

FIG. 5 depicts a side view of the MLB helmet pad 400 b of FIG. 4 . Tetrahedral lattice unit cells 403 can vary in size for different stiffness/softness in particular portions, such softer at an outer periphery and stiffer at a lower periphery.

FIG. 6 depicts a top view of a set 600 of example interchangeable MLB helmet pads 601 a - 604 a having tetrahedral lattice unit cells 605 and MLB helmet pads 601 b - 604 b having Voronoi lattice unit cells 605. A user can select a combination to suit a desired or required response to ballistic impact. FIG. 7 depicts a three-dimensional detail view of one MLB helmet pad 602 a of FIG. 6 . FIG. 8 depicts a bottom view of the set of MLB helmet pads 700 attached to an interior 702 of a tactical helmet 704.

FIG. 9 depicts a graphical chart 900 comparing back face deformation test results of a conventional helmet pad and the example MLB helmet pad. The average bullet strike test data shows a 66.69% improvement in backface deformation for the MLB helmet pad. FIG. 10 depicts a graphical chart 1000 comparing blunt impact test results of a conventional helmet pad and the example MLB helmet pad. The MLB helmet pad provides a 21.70% improvement over conventional helmet pads.

FIG. 11 depicts a top view of a hybrid set 1100 of example MLB helmet pads 1102 with a recessed top foam layer 1104. The foam layer 1104 can provide a comfort, can provide a hypoallergenic surface to skin, can provide sweat wicking properties, or other functions.

FIG. 12 depicts a top view of a set 1200 of MLB helmet pads 1202 that provide substantially full cranial coverage. FIG. 13 depicts a three-dimensional view of an example set 1200 a of the MLB helmet pads 1202 a having a first thickness. FIG. 14 depicts a three-dimensional view of an example set 1200 b of the MLB helmet pads 1202 b having a first thickness.

FIG. 15 depicts a three-dimensional view of the example set 1200 of the MLB helmet pads 1202 conformed to a cranium 1503 of a user 1505. FIG. 16 depicts a three-dimensional view of the example set 1200 of the MLB helmet pads 1202 attached inside a helmet 1507. FIG. 17 depicts a side cutaway view of the example set 1200 of the MLB helmet pads 1202 within the helmet 1507 worn on the cranium 1503 of the user 1505.

In one or more embodiments, the microlattice layers may be manufactured from additive manufacturing methods (AM). Such AM methods include VAT photopolymerization, material jetting, binder jetting, material extrusion or fuse deposition modelling (FDM), power bed fusion (e.g., direct metal laser sintering (DMLS), electron beam melting (EBM), selective heat sintering (SHS), selective laser melting (SLM), selective laser melting (SLS), sheet lamination, and/or directed energy disposition (DED), multi-jet fusion, digital light synthesis, and/or any combination thereof.

VAT polymerization method uses a vat of liquid photopolymer resin, out of which the microlattice structure can be constructed layer by layer. An ultraviolet (UV) light is used to cure or harden the resin where required, while a platform moves the microlattice structure being made downwards after each new layer is cured.

Material jetting approach can create a microlattice layer similar to using a two-dimensional ink jet printer. Material is jetted onto a build platform using either a continuous or Drop on Demand (DOD) approach. Material is jetted onto the build surface or platform, where it solidifies and the microlattice is built layer by layer. Material is deposited from a nozzle which moves horizontally across the build platform. The material layers are then cured or hardened using ultraviolet (UV) light.

The binder jetting approach uses two materials; a powder-based material and a binder. The binder acts as an adhesive between powder layers. The binder is usually in liquid form and the build material in powder form. A print head moves horizontally along the x and y axes of the machine and deposits alternating layers of the build material and the binding material. After each layer, the microlattice being printed is lowered on its build platform.

Fuse deposition modelling (FDM) is a common material extrusion process and is a technique used in domestic or hobby 3D printers. Material is drawn through a nozzle while under continuous pressure, where it is heated and is then deposited layer by layer into the desired cross-sectional area. The nozzle can move horizontally, and a platform moves up and down vertically after each new layer is deposited. Then the layers are fused together upon deposition as the material is in its melted state.

Powder bed fusion (PBF) methods use either a laser or electron beam to melt and fuse material powder together. All PBF processes involve the spreading of the powder material over previous layers into desired cross-sections. The powders are sintered, layer by layer. The platform lowers the microlattice to add additional layers, accordingly.

Directed Energy Deposition (DED) is a complex printing process commonly used to repair or add additional material to existing components. A typical DED machine consists of a nozzle mounted on a multi axis arm, which deposits melted material onto the specified surface and cross-section, where it solidifies. The process is similar in principle to material extrusion, but the nozzle can move in multiple directions and is not fixed to a specific axis. The material, which can be deposited from any angle due to 4 and 5 axis machines, is melted upon deposition with a laser or electron beam. The process can be used with polymers, ceramics but is typically used with metals, in the form of either powder or wire. Both conventional and additive manufacturing methods may be used together to create the desired microlattice layer, microlattice pads, and/or any combination thereof.

The microlattice structure may be manufactured with standard methods known in the art. In one or more embodiments, the microlattice structure may be fabricated by an additive manufacturing process to print a 3D matrix composite part utilizing a nanofunctionalization process created by HRL Laboratories. As disclosed in U.S. Pat. No. 8,663,539, entitled “Process of Making a Three-Dimensional Micro-Truss Structure,” which is incorporated by reference herein in its entirety, discloses a method that forms micro-trusses by using a fixed light input (collimated UV) light to cure (polymerize) polymer optical waveguides, which can self-propagate in a 3D pattern--the propagated polymer optical waveguides form the micro-truss. Furthermore, the microlattice structure may comprise at least a portion of materials such as a metal, polymer, foam and/or any combination thereof. More specifically, it may be a metal, such as magnesium, aluminum, titanium, chromium, iron, cobalt, nickel, copper, zinc and/or an alloy. The polymeric material may include polycarbone, aramid, high impact polysterene, nylon, ultra-high molecular weight polyethylene, poly (p-xylene), and/or any combination of such materials.

In one or more embodiments, the MLB helmet pads may be a single, continuous layer, and/or a plurality of modular segments. The MLB helmet pads may comprise uniform and/or non-uniform thicknesses, composition, and impact absorption properties. The MLB helmet pads may comprise an active or passive cooling system for thermal management--allowing evaporation of sweat through the active or passive cooling system. The MLB helmet pads may match or substantially match the contours of the wearer’s head.

In one or more embodiments, the MLB helmet pads may further comprise a comfort layer and/or comfort liner. The comfort layer and/or comfort liner may be coupled and/or fused to an outer surface and/or inner surface of the MLB helmet pads. Alternatively, the comfort layer and/or comfort liner may be coupled or fused to an inner surface of the tactical helmet. The comfort layer and/or comfort liner may comprise a single, continuous layer, and/or a plurality of modular comfort layer or liner segments. The comfort layer may comprise at least one microlattice layer. The comfort layer may further comprise at least one foam layer and/or at least one polymer layer. The polymer layer and/or the outer shell may comprise polycarbonate (PC), polyethylene (PE), high density polyethylene (HDPE), polypropylene (PP), ethylene vinyl acetate (EVA), ABS, polyurethane (PU) and/or any combination thereof.

The one or more microlattice layers and/or structures may further comprise a continuous, one-piece microlattice layer. The continuous, one-piece microlattice layer may be shaped and configured to any anatomical feature of the body. The continuous, one-piece microlattice layer may match or substantially match any anatomical feature of the body. In one embodiment, the microlattice layer comprises a continuous, one-piece microlattice layer that may be shaped and configured to a head of a wearer. The continuous, one-piece microlattice layer may match or substantially match the bones of the skull to maximize protection. Such regions comprise parietal, temporal, occipital, ethmoid, sphenoid, temporal, nasal, lacrimal, maxilla, zygomatic, mandible, and/or any combination thereof. The continuous, one-piece microlattice layer may comprise a uniform and/or non-uniform compressive strength and stiffness. The continuous, one-piece microlattice layer may comprise a uniform and/or non-uniform microlattice density. The continuous, one-piece microlattice layer comprises a uniform microlattice compressive strain. Alternatively, the plurality of microlattice segments or each of the plurality of microlattice segments may comprise a different microlattice compressive strain. The continuous, one-piece microlattice layer may be coupled to a surface of a protective garment.

The one or more microlattice layers and/or structures may further comprise a plurality of microlattice segments (not shown). The plurality of microlattice segments may be shaped and configured to any anatomical feature of the body. The plurality of microlattice segments or each of the plurality of microlattice segments may match or substantially match any anatomical feature of the body and/or at least one anatomical feature of the body. In one embodiment, the microlattice layer comprises a plurality of microlattice segments, the plurality of microlattice segments may be shaped and configured to a head of a wearer. The plurality of segments may match or substantially match the bones of the skull to maximize protection. Such regions comprise parietal, temporal, occipital, ethmoid, sphenoid, temporal, nasal, lacrimal, maxilla, zygomatic, mandible, and/or any combination thereof. The plurality of microlattice segments or each of the plurality of microlattice segments may comprise the same microlattice layer compressive strength and stiffness. Alternatively, plurality of microlattice segments or each of the plurality of microlattice segments may comprise a different compressive strength and stiffness. The plurality of microlattice segments or each of the plurality of microlattice segments may comprise the same microlattice density. Alternatively, the plurality of microlattice segments or each of the plurality of microlattice segments may comprise a different microlattice density. The plurality of microlattice segments or each of the plurality of microlattice segments comprises the same microlattice compressive strain. Alternatively, the plurality of microlattice segments or each of the plurality of microlattice segments may comprise a different microlattice compressive strain. The plurality of microlattice segments may be coupled to a surface of a protective garment.

In another embodiment, the microlattice layer may comprise microlattice pads or microlattice pad assemblies (not shown). The microlattice pad assemblies may comprise at least one microlattice layer and/or structure and at least one base layer. Alternatively, the microlattice pads may comprise a first base layer, a second base layer and a microlattice layer and/or structure. The microlattice pads or pad assemblies may further comprise one or more foam layers. Alternatively, the microlattice pads may comprise a microlattice layer and/or structure and one or more foam layers, the one or more foam layers coupled to a surface of the microlattice layer. The microlattice pads may further comprise one or more material layers. The one or more foam layers may be coupled to the microlattice layer and/or structure, and/or the one or more foam layers positioned between the first base layer and the second base layer. Accordingly, the one or more foam layers may be coupled to a surface of the at least one base layer, the first base layer, or the second base layer. In one embodiment, the microlattice layer and/or structure, one or more impact mitigation layers and/or one or more foam layers is disposed between the first base layer and the second base layer. The first base layer may be coupled to the second base layer to fully enclose the microlattice layer and/or structure, the microlattice layer and/or structure, one or more impact mitigation layers and/or one or more foam layers. The first base layer and the second base layer may comprise the same materials or different materials. The coupling may comprise adhesive, Velcro, melting, welding, thermoforming, and/or any combination thereof.

The one or more base layers may comprise any suitable material that is compatible with the filaments. For instance, one or more layers may comprise polymer materials (e.g., thermosets or thermoplastics), metal (e.g., aluminum or stainless steel), composites (e.g., carbon fiber, glass fiber reinforced polymer, fiberglass, or ceramic fibers), organic materials (e.g., wood, paper, or cardboard), ceramic cloth, natural cloth, polymeric cloth, metallic cloth, rubber, plastic, or any combination thereof.

As used herein, “filaments” may be used interchangeably to mean a plurality of filaments, an additional plurality of filaments, the adjacent filaments, and/or the plurality of interconnected filaments. In one embodiment, the filament unit height (H), filament unit cell height (H), filaments dimensions within the microlattice layer and/or structure may be varied. The filament unit height (H), filament unit cell height (H), filaments dimensions within the microlattice layer and/or structure may be the same throughout the microlattice layer for uniformity. Alternatively, the filament unit height (H), filament unit cell height (H), filaments dimensions within the microlattice layer and/or structure may be different in at least a portion of the microlattice layer and/or structure.

The filaments have a longitudinal axis, a width and/or diameter (W/D) and a length (L). In one or more embodiments, the width and/or diameter of the filaments comprises a range between 0.1 mm to 5 mm. The filaments length may be 0.3 mm to 25 mm, and/or 25 mm or greater. The filaments may further comprise an aspect ratio, the aspect ratio may be 3:1 or greater. The length of the filaments may be uniform and/or non-uniform along its longitudinal axis. In another embodiment, the filaments comprise a cross-section within the microlattice layer and/or structure and the cross-section may be varied. The filaments may comprise a cross-section, the cross-section being solid or hollow. The solid or hollow cross-section may be uniform or substantially uniform along the longitudinal axis. Alternatively, the solid or hollow cross-section may be non-uniform or substantially non-uniform along the longitudinal axis. The cross-section comprises a circle, an oval, a regular polygon and/or an irregular polygon. The polygons comprise a triangle, a square, a rectangle, a pentagon, a hexagon, a septagon, an octagon, a nonagon, a decagon, and/or any combination thereof. The filaments having a uniform and/or a non-uniform cross-section along the longitudinal axis. The non-uniform cross-section comprises a frustum or tapered cross-section, and/or undulated cross-section. In one or more embodiments, the cross-section may further comprise a cross-sectional area, the cross-sectional area is 0.01 mm² or greater, 1 mm² or greater, 10 mm² or greater, 20 mm² or greater. Accordingly, the cross-sectional area is between 0.01 to 1 mm², or between 1 to 10 mm², or between 10 to 20 mm² or between 0.01 to 20 mm².

The at least one base layer, the first base layer and/or the second base layer may comprise a foam material, Velcro material, a 2-way stretch, a 4-way stretch, a polymer, and/or any combination thereof. The foam layer may comprise a foam material, the foam material comprising polymeric foams, quantum foam, polyethylene foam, polyurethane foam (PU foam rubber), XPS foam, polystyrene, phenolic, memory foam (traditional, open cell, or gel), impact absorbing foam, compression foam, latex rubber foam, convoluted foam (“egg create foam”), EVA foam, VN 600 foam, Evlon foam, Ariaprene or Ariaprene-like material, PORON XRD, impact hardening foam, and/or any combination thereof. The at least one foam layer may have an open-cell structure or closed-cell structure. The foam layer can be further tailored to obtain specific characteristics, such as anti-static, breathable, conductive, hydrophilic, high-tensile, high-tear, controlled elongation, and/or any combination thereof. The foam material may be uniform throughout the microlattice layer, and/or non-uniform throughout the microlattice layer. The one or more foam layers may comprise a single, continuous piece, and/or a plurality of foam segments. The polymer may comprise polycarbonate (PC), polyethylene (PE), high density polyethylene (HDPE), polypropylene (PP), ethylene vinyl acetate (EVA), ABS, polyurethane (PU) and/or any combination thereof.

In some embodiments, the Young’s modulus of the material used to fabricate the filaments 900 can be at least 1 MPa, at least 10 MPa, at least 100 MPa, at least 1000 MPa, and/or at least 10,000 MPa. In other embodiments, the Young’s modulus comprises between 1 MPa and 100 MPa, between about 1 MPa and 1000 MPa, between 1 MPa and 10,000 MPa, between 10 MPa and 1000 MPa, between 10 MPa and 10,000 MPa, and/or any combination thereof. Also, the Young’s modulus can be between 100 MPa to 1000 MPa and 1000 MPa to 10,000 MPa. In some instances, the ratio of the Young’s modulus of the material used to fabricate the filaments 900 can be at least about 0.001:1, at least about 0.01:1, at least about 0.1:1, at least about 1 :1, at least about 10:1, at least about 100 :1, at least about 1000 :1 and/or less than about 10,000.00:1, less than about 1000 :1, less than about 100 :1, less than about 10:1, less than about 1:1, less than about 0.1:1, or less than about 0.01:1.

It must be noted that, as used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to a “colorant agent” includes two or more such agents.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although a number of methods and materials similar or equivalent to those described herein can be used in the practice of the present invention, the preferred materials and methods are described herein.

As will be appreciated by one having ordinary skill in the art, the methods and compositions of the invention substantially reduce or eliminate the disadvantages and drawbacks associated with prior art methods and compositions.

It should be noted that, when employed in the present disclosure, the terms “comprises,” “comprising,” and other derivatives from the root term “comprise” are intended to be open-ended terms that specify the presence of any stated features, elements, integers, steps, or components, and are not intended to preclude the presence or addition of one or more other features, elements, integers, steps, components, or groups thereof.

As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure.

While it is apparent that the illustrative embodiments of the invention herein disclosed fulfill the objectives stated above, it will be appreciated that numerous modifications and other embodiments may be devised by one of ordinary skill in the art. Accordingly, it will be understood that the appended claims are intended to cover all such modifications and embodiments, which come within the spirit and scope of the present invention. 

What is claimed is:
 1. A helmet pad comprising: a substrate having a first side attachable to an interior surface of a helmet; an outer lattice layer peripherally attached to a second side of the substrate, the second side opposite to the first side, the outer lattice layer comprising fibers attached in one of: (i) a Voronoi lattice unit cells; and (ii) tetrahedral lattice unit cells; and padding material received in an enclosure between the second surface of the substrate and the outer lattice layer.
 2. The helmet pad of claim 1, wherein the padding material comprises one or more internal lattice layers peripherally attached to the second side of the substrate, the one or more internal lattice layers each comprising fibers attached in one of: (i) a Voronoi lattice unit cells; and (ii) tetrahedral lattice unit cells.
 3. A helmet comprising: a helmet shell; and one or more helmet pads, each pad comprising: a substrate having a first side attachable to an interior surface of a helmet, an outer lattice layer peripherally attached to a second side of the substrate, the second side opposite to the first side, the outer lattice layer comprising fibers attached in one of: (i) a Voronoi lattice unit cells; and (ii) tetrahedral lattice unit cells; and padding material received in an enclosure between the second surface of the substrate and the outer lattice layer.
 4. The helmet of claim 3, wherein the padding material comprises one or more internal lattice layers peripherally attached to the second side of the substrate, the one or more internal lattice layers each comprising fibers attached in one of: (i) a Voronoi lattice unit cells; and (ii) tetrahedral lattice unit cells. 